Inching device



June 8, 1954 Filed May 9, 1951 S. H. KAST INCHING DEVICE 2 Sheets-Sheet l i BY ff 8S f6 @am June 8, 1954 s. H. KAST 2,680,795

INCHING DEVICE Filed May 9, 1951 2 Sheets-Sheet 2 @www Patented June 8, Y1954 IN CHING DEVICE Samuel H. Kast, Latrobe, Pa., assignor, by mesne assignments, to I-T-E Circuit Breaker Colnpany, Philadelphia, Pa., a corporation of Penn- Sylvania Application May 9, 1951, Serial No. 225,330

vserve only to sectionalize electric circuits, not to open circuits when a current iiows in them. That is, disconnect switches should be opened only -under no load condition. But it sometimes happens that due to an operators mistake or for other reasons, a disconnect switch is opened under load. Such faulty operation can result in total destruction of the disconnect switch and in considerable harm or even death to the operator.

A possible remedy to this faulty operation oi the disconnect switch would be to instruct the switch operators to first open the disconnect switch by a very small amount and if any arc is drawn to immediately step the switch closed; if on the other hand, no arc is drawn the disconnect switch can afterwards be completely opened. The main shortcoming of this remedy is the human element in that an operator can still pull a disconnect switch all the way in one operation, regardless of the many instructions given him on the subject.

My present invention provides a safety device for opening disconnect switches that makes possible the correct opening of a disconnect switch without relying on any human element.

When my novel device is installed on a disconnect switch, the disconnect switch can be opened completely only after it has been opened by a small amount, thus permitting the operator to notice whether an arc has been drawn and if an arc is drawn to step the disconnect switch back in the closed position or if no arc is drawn to completely open the disconnect switch.

My safety device, hereinafter referred to as an inching device, consists essentially of a latch member having a beveled surface and a slot to receive its pivot which is supported by a stationary member attached to the base of the switch hinge. This support also has an eccentric pin for proper latching adjustment and a spring attached to the base to keep Ithe latch in proper position.

In the switch closed position, the latch engages a latch pin attached to the blade of the disconnect switch.

As the switch is opened, the latch pin comes in contact with the upper part of the latch and forces it to slide on the pivot away from the base of the switch hinge until it is stopped by the end of the slot in the latch. The opening of the blade is thus restricted to the formation of a small gap between it and the pin of the disconnect switch.

When the operator has ascertained the correctness of operation, it is only necessary to move the blade slightly in the opposite direction -to permit disengaging the latch from the latch pin. The spring, no longer opposed by the eccentric pin, then forces the latch away from the latch pin permitting completion of the opening operation.

Accordingly, the main object of my present invention is the provision of a safety device for a disconnect switch to protect operators and equipment from a faulty operation of the disconnect switch.

Another object of my present invention is the provision of means whereby the disconnect switch can be fully opened only after a previous trial opening to ascertain whether the disconnect switch is being opened under load or not.

More particularly, an object of my present invention is the provision of means whereby a disconnect switch, during its opening operation, must rst be opened by a small amount and, if the operation is found to be correct, can then be fully opened.

A further object of my present invention is the provision of an inching device for disconnect switches that can be easily applied to disconnect switches of all voltage ratings.

Another object of my present invention is an inching device using a minimum amount oi parts so that its application on disconnect switches will increase the cost of disconnect switches by only a very small amount.

These and other objects and advantages of my present invention will be apparent from the following specification when taken with the accompanying drawings in which:

Figure l is a disconnect switch incorporating the inching device of my invention.

Figure 2 is a plan view of the switch hinge showing the inching device of my invention in the switch closed position.

Figure 3 is a sectional View of the switch hinge showing the inching device of my invention in the switch closed position.

Figure 4 is an end View of the switch hinge showing the inching device of my invention in the switch closed position.

Figure 5 is a sectional view of the switch hinge v26 on insulator |53.

showing the position of the inching device of my invention during the trial opening of the disconnect switch.

Figure 6 is a sectional view of the switch hinge showing the position of the inching device of my invention when the switch is ready to be fully opened.

Referring now to Figures 1, 2, 3 and 4 showing, respectively, a hook operated disconnect switch incorporating my present invention, a plan view of the switch hinge, a sectional view of the switch hinge and an end view of the switch hinge, the disconnect switch is here shown above frame i and supported on frame by two insulators i2 and I3 suitably mounted on frame H, for example, by means of bolts and nuts I5. Switch l0 is here shown in an inverted position since in actual practice switch it would be under frame suspended from frame by means of insulators l2 and |3.

More precisely, the hinge of the disconnect vswitch it and the hinge terminal pad 2| are mounted by appropriate means, for example, bolt and nut (not shown) placed in opening 22 on insulator I2, while the jaw 25 of switch I0 is mounted also by appropriate bolts and nuts Insulator |'3 carries also the switch terminal pad 21 suitably mounted on insulator |3 and in good electrical contact with jaw 25.

Blade of disconnect switch |43 is mounted on and suitably secured to a forked member 3| having two transverse openings 32. Transverse openings 32 receive shaft 33 which is supported on hinge member 28, thus permitting rotation of blade 30 around shaft 33 with respect to hinge 20. The other end 35 of blade 38 is suitably shaped to provide a high pressure contact engagement with jaw 25 and has an extension d0 which terminates in an aperture il for the reception of a hook stick operating member (not shown).

The inching device 50, shown more clearly in Figures 2 and 3, consists mainly of a support 55 attached to the base 56 of hinge 20 by suitable means, for example, screws 51 and 58. Support 55 has two similarly shaped extensions 58 and 5| each having an opening 55 at their ends 6E and 61.

Slightly below these openings 55 is an eccentric pin 10 secured to support 55 and extending from extension 58 to extension 5|. Support extensions 58 and 8| hold the latch 'i5 of the inching device 56 by means of a pivot 16 held in openings of extensions 58 and 5|. This pivot.

and 58 biases latch 15 in the clockwise direction and in the switch closed position its biasing action is limited by the action of the eccentric pin 10 against the beveled part 88 of the latch 15. A latch pin of quadrangular section extends transversely across the forked member 3i and serves to be engaged by the hooks Sil and of .the latch 15 is approximately in the vertical position, being biased clockwise by leaf spring 00 against eccentric pin 10 which operates as a stop pm.

Furthermore, latch 15 is in its middle position since pivot 16 is just in the middle of slot 80 of latch 15. Latch 15 and latch pin |00 are now inoperative.

At the initial opening of blade 30 by means of a hook stick (not shown) placed in eye 4| of extension 4G of blade 30, the latch pin |00 secured to fork 3| and, therefore, movable with blade 30 moves up engaging hooks 84 and 85 of latch 15, therefore pulling latch 15 in the upward direction until latch 15 is stopped by the end of travel of pivot 16 in slot 80 of latch 15. Latch 15, although biased by leaf spring 90, cannot rotate clockwise around pivot 16 because the upper portion of latch pin |00 is still in engagement with the upper part of hooks 84 and 85.

At this point, the blade 30 has been rotated by a few degrees and its contacts 35 go out of engagement with jaw 25, that is, a small air gap is produced between blade contacts 35 and jaw 25.

If at this point the operator notices an arc between blade Contact member 35 and jaw 25, he can step the blade 30 back in the closed position without causing any harm to him or damage to the equipment.

If, on the other hand, no arc is drawn, that is, if the opening operation is correct, he can now open the switch completely by rst operating the blade 30 slightly toward the switch closed position and then pulling the switch blade 30 in the fully opened position.

As the blade 30 (see Figure 6) is now pushed slightly toward the closed position, leaf spring 9D opposed neither by eccentric pin 10 nor by latch pin |80, rotates latch 15 clockwise out of engagement with latch pin |00, thus freeing the blade 30 for further counterclockwise rotation toward its full open position.

At closing, the latch pin |00 rst comes in contact with the lower portion of hooks 84 and 85 of latch 15, thus pushing latch 15 downwardly and by the combined action of leaf spring and eccentric pin 10, the latch 15 goes back in the position shown in Figure 3.

It is easily seen that any other biasing means could be substituted for the leaf spring 98 as long as the biasing action tends to move latch 15 against eccentric pin 10.

It is also evident that lach 15 with spring 90 and support 55 can be placed on the movable part 30-3|, while the latch pin |00 can be placed on the hinge base 56 without changing in any way the operation of my inching device 50.

It is also evident that the amount of air gap permissible at the trial opening of the disconnect switch ||l will depend on the rating of the switch, the air gap being small for heavy load switches and larger in smaller switches. This regulation of the air gap can be easily obtained by my inching device 50 by the appropriate shaping of slot 80 or by properly locating latch pin |58 in the blade section 3|.

It is further evident that my inching device 50 can be used in any equipment in which the full open position must be preceded by a trial opening to determine whether the operation is correct and not only in disconnect switches, although I have here described the operation of my inching device 50 in connection with the operation of a disconnect switch.

In the foregoing I have described my invention solely in connection with specific illustrative embodiments thereof. Since many variations and modifications of my invention will now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosures herein contained but only by the appended claim.

I claim:

In a disconnect switch having a movable contact member and a frame; said disconnect switch having a close, and intermediate, and full open position; a latch pin attached to said movable contact member and extending in a direction perpendicular thereto; an inching device comprising a latch, a support mounted on said frame; a pivot secured to said support; said latch having a slot; said slot receiving said pivot; said pivot being perpendicular to said movable contact member; a stop pin; said stop pin being secured to said support; a leaf spring; said leaf spring secured to said frame and exerting a force on said latch at a point between said pivot and said latch pin; said leaf spring biasing said latch against said stop pin and in a direction parallel to the plane of movement of said movable contact member; said stop pin in cooperation with said leaf spring maintaining said latch and said latch pin in proper latching adjustment during the initial operation of said disconnect switch; said latch pin engaging said latch during the initial opening operation of said disconnect switch and limiting the travel of said movable contact member toward the full open position; said latch pin also pulling said latch in the direction of movement of said movable contact member and said latch pin; said leaf spring rotating said latch around said pivot and disengaging said latch from said latch pin when said movable contact member is moved a small distance toward Y said closed position after said initial opening to thereby enable said movable contact member to be moved to said full open position.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name 

